WASHINGTON - (AP) - A somber President Barack Obama led a momentof silence today for a nation stunned by an attemptedassassination against an Arizona congresswoman that left herseriously wounded, several other injured and six people dead.

On a frigid Washington morning, the president and first ladyMichelle Obama walked out of the White House to the sounding of abell at 11 a.m. Both wearing overcoats, they stood next to eachother on the South Lawn, each with their hands clasped, heads bowedand eyes closed.

After a minute of silence, they walked inside, the president'shand on the first lady's back.

The moment was marked on the steps of the U.S. Capitol andaround the nation on the direction of the president, who called forthe country to come together in prayer or reflection for thosekilled and those fighting to recover. In total, 19 people were shotin the shooting rampage in Tuscon, Ariz. on Saturday. DemocraticRep. Gabrielle Giffords was shot point-blank in the head, and sheremains in intensive care. Among the six people killed wereArizona's chief federal judge, a 9-year-old girl interested ingovernment, and one of Giffords' aides. Giffords' orbitingbrother-in-law, astronaut Scott Kelly, called for a moment ofsilence aboard the International Space Station and at all theflight control centers around the world.

Arizona congresswoman shot, several killed in Tucson